Materials and Methods: The population of the study included 780 patients undergoing coronary angiography out of whom 547 cases were entered into this case-control study. The subjects were then divided into 5 groups based on the severity of coronary artery involvement: with the least or no involvement (control group), one artery involved (group 1), 2 arteries involved (group 2), 3 arteries involved (group 3), and severe diffuse involvement of all coronary arteries (group 4). Residences of the patients were located from their medical history and then 200-mL of drinking-water samples were then taken from each area in plastic containers. Next, the levels of calcium and magnesium were measured using the EDTA method. Finally, the samples were divided into 4 groups based on the hardness of water.

Results:The mean age of the participants was 59.7 years and the most frequent type of water in the residential areas was the soft water. Further, the highest frequency related to the severity of atherosclerosis belonged to groups 4 and 3, respectively. Based on the results, no significant relationship was found either between the severity of atherosclerosis and calcium level of water or the severity of atherosclerosis and magnesium level of water.

Conclusions: In general, the results revealed that there was no significant relationship between the levels of calcium and magnesium in the drinking water of the patients residing in East Azerbaijan province and their severity of atherosclerosis. The findings further suggest that the drinking water of the province can be divided into hard and soft water and the severity of atherosclerosis of the patients is independent of the hardness of the drinking water in their residences.